Fructobacillus fructosus OS-1010 strain stimulates intestinal cells to secrete exosomes that activate muscle cells

Fructobacillus is a lactic-acid bacterium recently identified in fructose-rich environments. Fructobacillus is also known to exhibit unusual growth characteristics due to an incomplete gene encoding alcohol/acetaldehyde hydrogenase, which results in an imbalance in the nicotinamide adenine mononucleotide (NAD⁺)/NADN levels. Recently, the addition of d-fructose to the culture medium of Fructobacillus strains increased the intracellular nicotinamide mononucleotide (NMN) content. In the present study, we evaluated the functionality of Fructobacillus that produces high levels of NMN, using one substrain (Fructobacillus fructosus OS-1010). Therefore, in this study, we examined its functionality in the interaction between intestinal cells and muscle cells. The results showed that supernatant derived from intestinal epithelial cells (Caco-2 cells) treated with F. fructosus OS-1010 activated muscle cells (C2C12 cells). Further analysis revealed that Caco-2 cells treated with F. fructosus OS-1010 secreted exosomes known as extracellular vesicles, which activated the muscle cells. Furthermore, pathway analysis of the target genes of miRNA in exosomes revealed that pathways involved in muscle cell activation, including insulin signaling and cardiac muscle regulation, neurotrophic factors, longevity, and anti-aging, can be activated by exosomes. In other words, F. fructosus OS-1010 could activate various cells such as the skin and muscle cells, by secreting functional exosomes from the intestinal tract.